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  • Committer: Teddy Hogeborn
  • Date: 2015-05-23 20:18:34 UTC
  • mto: This revision was merged to the branch mainline in revision 756.
  • Revision ID: teddy@recompile.se-20150523201834-e89ex4ito93yni8x
mandos: Use multiprocessing module to run checkers.

For a long time, the Mandos server has occasionally logged the message
"ERROR: Child process vanished".  This was never a fatal error, but it
has been annoying and slightly worrying, since a definite cause was
not found.  One potential cause could be the "multiprocessing" and
"subprocess" modules conflicting w.r.t. SIGCHLD.  To avoid this,
change the running of checkers from using subprocess.Popen
asynchronously to instead first create a multiprocessing.Process()
(which is asynchronous) calling a function, and have that function
then call subprocess.call() (which is synchronous).  In this way, the
only thing using any asynchronous subprocesses is the multiprocessing
module.

This makes it necessary to change one small thing in the D-Bus API,
since the subprocesses.call() function does not expose the raw wait(2)
status value.

DBUS-API (CheckerCompleted): Change the second value provided by this
                             D-Bus signal from the raw wait(2) status
                             to the actual terminating signal number.
mandos (subprocess_call_pipe): New function to be called by
                               multiprocessing.Process (starting a
                               separate process).
(Client.last_checker signal): New attribute for signal which
                              terminated last checker.  Like
                              last_checker_status, only not accessible
                              via D-Bus.
(Client.checker_callback): Take new "connection" argument and use it
                           to get returncode; set last_checker_signal.
                           Return False so gobject does not call this
                           callback again.
(Client.start_checker): Start checker using a multiprocessing.Process
                        instead of a subprocess.Popen.
(ClientDBus.checker_callback): Take new "connection" argument.        Call
                               Client.checker_callback early to have
                               it set last_checker_status and
                               last_checker_signal; use those.  Change
                               second value provided to D-Bus signal
                               CheckerCompleted to use
                               last_checker_signal if checker was
                               terminated by signal.
mandos-monitor: Update to reflect DBus API change.
(MandosClientWidget.checker_completed): Take "signal" instead of
                                        "condition" argument.  Use it
                                        accordingly.  Remove dead code
                                        (os.WCOREDUMP case).

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  return plaintext_length;
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}
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__attribute__((warn_unused_result, const))
 
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static const char *safe_string(const char *str){
 
498
  if(str == NULL)
 
499
    return "(unknown)";
 
500
  return str;
 
501
}
 
502
 
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__attribute__((warn_unused_result))
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static const char *safer_gnutls_strerror(int value){
498
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  const char *ret = gnutls_strerror(value);
499
 
  if(ret == NULL)
500
 
    ret = "(unknown)";
501
 
  return ret;
 
506
  return safe_string(ret);
502
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}
503
508
 
504
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/* GnuTLS log function callback */
513
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                              const char *seckeyfilename,
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                              mandos_context *mc){
515
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  int ret;
 
521
  unsigned int uret;
516
522
  
517
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  if(debug){
518
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    fprintf_plus(stderr, "Initializing GnuTLS\n");
569
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                 safer_gnutls_strerror(ret));
570
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    goto globalfail;
571
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  }
 
578
  if(mc->dh_bits == 0){
 
579
    /* Find out the optimal number of DH bits */
 
580
    /* Try to read the private key file */
 
581
    gnutls_datum_t buffer = { .data = NULL, .size = 0 };
 
582
    {
 
583
      int secfile = open(seckeyfilename, O_RDONLY);
 
584
      size_t buffer_capacity = 0;
 
585
      while(true){
 
586
        buffer_capacity = incbuffer((char **)&buffer.data,
 
587
                                    (size_t)buffer.size,
 
588
                                    (size_t)buffer_capacity);
 
589
        if(buffer_capacity == 0){
 
590
          perror_plus("incbuffer");
 
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          free(buffer.data);
 
592
          buffer.data = NULL;
 
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          break;
 
594
        }
 
595
        ssize_t bytes_read = read(secfile, buffer.data + buffer.size,
 
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                                  BUFFER_SIZE);
 
597
        /* EOF */
 
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        if(bytes_read == 0){
 
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          break;
 
600
        }
 
601
        /* check bytes_read for failure */
 
602
        if(bytes_read < 0){
 
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          perror_plus("read");
 
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          free(buffer.data);
 
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          buffer.data = NULL;
 
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          break;
 
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        }
 
608
        buffer.size += (unsigned int)bytes_read;
 
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      }
 
610
      close(secfile);
 
611
    }
 
612
    /* If successful, use buffer to parse private key */
 
613
    gnutls_sec_param_t sec_param = GNUTLS_SEC_PARAM_ULTRA;
 
614
    if(buffer.data != NULL){
 
615
      {
 
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        gnutls_openpgp_privkey_t privkey = NULL;
 
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        ret = gnutls_openpgp_privkey_init(&privkey);
 
618
        if(ret != GNUTLS_E_SUCCESS){
 
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          fprintf_plus(stderr, "Error initializing OpenPGP key"
 
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                       " structure: %s", safer_gnutls_strerror(ret));
 
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          free(buffer.data);
 
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          buffer.data = NULL;
 
623
        } else {
 
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          ret = gnutls_openpgp_privkey_import(privkey, &buffer,
 
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                                            GNUTLS_OPENPGP_FMT_BASE64,
 
626
                                              "", 0);
 
627
          if(ret != GNUTLS_E_SUCCESS){
 
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            fprintf_plus(stderr, "Error importing OpenPGP key : %s",
 
629
                         safer_gnutls_strerror(ret));
 
630
            privkey = NULL;
 
631
          }
 
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          free(buffer.data);
 
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          buffer.data = NULL;
 
634
          if(privkey != NULL){
 
635
            /* Use private key to suggest an appropriate sec_param */
 
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            sec_param = gnutls_openpgp_privkey_sec_param(privkey);
 
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            gnutls_openpgp_privkey_deinit(privkey);
 
638
            if(debug){
 
639
              fprintf_plus(stderr, "This OpenPGP key implies using a"
 
640
                           " GnuTLS security parameter \"%s\".\n",
 
641
                           safe_string(gnutls_sec_param_get_name
 
642
                                       (sec_param)));
 
643
            }
 
644
          }
 
645
        }
 
646
      }
 
647
      if(sec_param == GNUTLS_SEC_PARAM_UNKNOWN){
 
648
        /* Err on the side of caution */
 
649
        sec_param = GNUTLS_SEC_PARAM_ULTRA;
 
650
        if(debug){
 
651
          fprintf_plus(stderr, "Falling back to security parameter"
 
652
                       " \"%s\"\n",
 
653
                       safe_string(gnutls_sec_param_get_name
 
654
                                   (sec_param)));
 
655
        }
 
656
      }
 
657
    }
 
658
    uret = gnutls_sec_param_to_pk_bits(GNUTLS_PK_DH, sec_param);
 
659
    if(uret != 0){
 
660
      mc->dh_bits = uret;
 
661
      if(debug){
 
662
        fprintf_plus(stderr, "A \"%s\" GnuTLS security parameter"
 
663
                     " implies %u DH bits; using that.\n",
 
664
                     safe_string(gnutls_sec_param_get_name
 
665
                                 (sec_param)),
 
666
                     mc->dh_bits);
 
667
      }
 
668
    } else {
 
669
      fprintf_plus(stderr, "Failed to get implied number of DH"
 
670
                   " bits for security parameter \"%s\"): %s\n",
 
671
                   safe_string(gnutls_sec_param_get_name(sec_param)),
 
672
                   safer_gnutls_strerror(ret));
 
673
      goto globalfail;
 
674
    }
 
675
  } else if(debug){
 
676
    fprintf_plus(stderr, "DH bits explicitly set to %u\n",
 
677
                 mc->dh_bits);
 
678
  }
572
679
  ret = gnutls_dh_params_generate2(mc->dh_params, mc->dh_bits);
573
680
  if(ret != GNUTLS_E_SUCCESS){
574
 
    fprintf_plus(stderr, "Error in GnuTLS prime generation: %s\n",
575
 
                 safer_gnutls_strerror(ret));
 
681
    fprintf_plus(stderr, "Error in GnuTLS prime generation (%u bits):"
 
682
                 " %s\n", mc->dh_bits, safer_gnutls_strerror(ret));
576
683
    goto globalfail;
577
684
  }
578
685
  
1900
2007
}
1901
2008
 
1902
2009
int main(int argc, char *argv[]){
1903
 
  mandos_context mc = { .server = NULL, .dh_bits = 1024,
 
2010
  mandos_context mc = { .server = NULL, .dh_bits = 0,
1904
2011
                        .priority = "SECURE256:!CTYPE-X.509:"
1905
 
                        "+CTYPE-OPENPGP", .current_server = NULL,
 
2012
                        "+CTYPE-OPENPGP:!RSA", .current_server = NULL,
1906
2013
                        .interfaces = NULL, .interfaces_size = 0 };
1907
2014
  AvahiSServiceBrowser *sb = NULL;
1908
2015
  error_t ret_errno;